Generator voltage regulator



May 9, 1944. J R Y 2,348,571-

GENERATOR VOLTAGE REGULATOR Filed Nov. 26, 1941 2 Sheets-Sheet 1 Q 37 6/ as '52 4a 1, 4/ 2 75 4 6 I o \O 4 42 45 l j 33 35 5 lNVENTOR W/u/AM J m 1 I MMHJL l/is ATTORNEYS May 9, 1944. w J RADY 2,348,571

GENERATOR VOLTAGE REGULATOR Filed NOV. 26, 1941 2 Sheets-Shet 2 83 a2 a/ a! a5 J0 92' -97 77F 1 M/ LL/AM J Rem hls HT TDHNE Y5 Patented May 9, 1944 UNITED STATES PATENT OFFICE GENERATOR VOLTAGE REGULATOR William J. Rady, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 26, 1941, Serial No. 420,571 Claims. (Cl. 201-48) This invention relates to a battery chargi battery. The ability of the metal container to system and more particularly for automobile use absorb heat is commensurate with the heat ab- W c c t e ine drives a generator which sorbing ability of the elements within the storage es a storage battery in which electrical enbattery, namely the plates and the electrolyte. c y is accumulated for the pu p of Operating 5 I do not mean to say that the thermostat enclosan engine starter o fo supplyin electric cur-- ing metal container of my invention has a heat rent to lamps when the engine is not running. absorbing ability equal in value to the heat ab- It is an object of the invention to provide imsorbing ability of the elements within a storage proved means for controlling the amount of battery case, but I wish to have it understood charging current in accordance with battery that the effect of the metal container upon the temperature. It is well known that the charging thermostat is the same as would be the case if voltage of a storage battery is higher when cold the thermostat were placed within a battery cell. than hot; therefore means have been provided Also I wish to have it understood that whereas for controlling the generator voltage regulator the total heat insulating value of the jacket for in such manner that the maximum voltage will 5 the metal container is not necessarily equal to be greater when the battery is cold and less when the total heat insulating value of a storage bat the battery is hot. This has been accomplished tery case. the efiect upon the thermostat by by placing a thermal switch inside the storage the heat insulating jacket of my invention is the battery and bringing leads out through the walls same as the heat insulating effect of the storage of the battery to connect with a resistance unit battery case upon the thermostat placed therein. by which the circuit of the electromagnet of the Further objects and advantages of the present voltage regulator may be controlled. The use invention will be apparent from the following of a thermostat located within the storage batdescription, reference being bad to the accomtery complicates the construction of the battery panying drawings wherein a preferred embodiand requires the disconnection of additional wires ment of the present invention is clearly shown. whenever the battery is removed for recharging In the drawings: at a service station. Fig. 1 is a wiring diagram showing the location It is an object of the present invention to proof the thermal switch of my invention. vide for the protection of a storage battery Fig. 2 is a sectional view of one form of thermal against it being charged at an excessive rate switch embodying the present invention. when the battery is hot without the use of any Fig. 3 is a fragmentary view showing a plan devices which are mounted within or upon the view of the thermal switch and its metal constorage battery. In order to accomplish this obtainer in section, ject I mount the thermostat which controls the F g. 4 s a f t y end view looking in the generator voltage regulator in a container which direction of arrow 4 of Fig. 2. can be mounted near the storage battery so as Fig. 5 is a side view partly in longitudinal secto be subjected to the same environment temtion of another form of thermal switch. perature, and I construct this container in such Fig. 6 is a sectional view on line 66 of Fig. 5. a manner that the thermostat will operate sub- Fig. 7 is an end view. stantially according to its manner of operation if Fig. 8 is a sectional view on line 8-43 of Fig. 6. it were mounted within the battery, Referring to Fig. 1, a storage battery 20 The thermostat container is a metal body havgrounded at 2! is connected by wire 22 and a ing relatively thick walls which are capable of relay 23 with a generator 24 grounded at 25. absorbing and storing a substantial amount of Generator field 26 is connected to ground 21 heat some of which is received by the air within through a contact 28, a movable contact 29 and the metal body in order to operate the thermoarmature 3i! of a generator regulator. When the stat. The metal container is enclosed in a jacket contact 29 is separated from the contact 28, the of material having relatively low heat conductivfield 25 is connected to ground through a reity in order to retard the increase of the temperasistance 3!. The armature 3b is attracted by ture of the metal body with. respect to increasing an electromagnet comprising a core 32 and a the temperature of the surrounding atmosphere. The amount of retardation of heat transfer to the metal body is substantially the same as the amount of retardation of heat transfer which would be afforded by the walls of the storage winding One end of the winding 33 is connected to ground 21, the other end of the winding is connected to the terminal 34 by wire 35. A resistance 36 connected to terminal 34 with the terminal 31 connected by wire 38 with an ignition switch connected by wire 4!] with wire 22. The terminal Bl i connected by a wire 41 to a bimetallic strip 62 carrying a movable contact 43 engageable with a stationary contact 44 which is connected by wire 45 to the terminal The contacts 43 and 44 are normally separated when the battery is cold. The operation of the circuit is as follows: When the generator 24 is operating above a certain speed at which its voltage is sufficient to cause the relay 23 to close, its charging voltage is limited by the voltage regulator. If, for example, the battery 20 is rated as a fi volt battery, the regulator may be set to limit the charging voltage at 8-volts when the battery is cold. When the battery temperature attains a certain value, the thermal switch con-- tacts 43 and 44 will close, thus short circuiting the resistanc 36 and reducing the voltage at which the regulator will begin to regulate. The voltage may be reduced to seven or six and a half volts if desired, depending upon the value of the resistance 35. The thermal switch and the resistance 36 are constructed as a unit designated by the dot-dash line rectangle 50.

If desired the thermal switch may be a multistage device which shorts-out the resistance 36 in sections, for example, a two-stage device which shorts-out part of the resistance 38 at a thermostat temperature of around 100 F. and he remainder of the resistance at 125 F. Such a thermal switch would aiford battery protection under hot weather conditions which are not unusual as well as under conditions of excessive heat as encountered in the tropical and subtropical deserts.

Referring now to Figs. 2 and 3, I have shown one specific construction of the unit 50 embodying my present invention. The unit 58 comprises a base or closure of insulating material and upon which a bracket 52 is mounted. The bracket is anchored to the inside of the closure 5| by a rivet 54. On the outside of the closure end electrically connected to the rivet 54, and hence to the bracket 52, is the electric conductor or wire 45. A screw 55 having threaded engagement with a tapped hole in the bracket 52 carries the stationary contact 44. By turning the screw 55 of the stationary contact may be screwed in and out of the bracket for the purpose of adjusting the stationary contact relative to the movable contact 43.

The movable contact 43 carried by the bimetallic element 42, normally separated from the stationary contact, is adapted to make electric connection with the contact 44. The bimetallic element is secured at one end to the bracket 52 through a rivet 56 extending through an insulating bushing 51 and upset at 58 to hold the element 42 in assembled relation with the bracket 52. The head of the rivet 56 is an electrical connection with the element 42. The bimetallic element is also electrically connected with the wire or conductor 4! which passes through an opening in the closure 5|.

The thermal switch assembly is mounted within a chamber 8! provided by a heat absorbing case 60 having relatively thick walls. For small volume, the material of the so should have high specific heat and density. Porcelain and iron are very good. A zinc die-casting is also suitable and may be easily manufactured. The open end of the case 60 is formed to provide a shoulder 62 and a circular flange 53 within which the closure 5| is positioned with the base resting upon the shoulder 52. The flange 63 is spun over the outer surface of the closure, Fig. 3, to secure rigidly the latter against the shoulder 62. This unit is now ready to be assembled within a housing comprising a tube H closed at the bottom by a disc 12 joined to the tube by an annular flange 13 which may be soldered. The tube H is welded to a mounting bracket 14 having apertured ears 14a.

In the present instance it is desirable to support the resistance element 38 exterior of a cover 15 which closes the open end of the tube H. In order that the thermal switch assembly may be inserted a substantial distance within the casing without breaking the electrical connections the wires 4| and are provided with a certain amount of slack. The ends of the conductor wires 4| and 45 are respectively connected to the terminals 31 and 34 which project through the cover 15 and are insulated therefrom. The terminals El and 34 support a bar of non-conducting material, around which is wound the resistance wire 35, having one end electrically connected with the terminal 3! and the other end to the terminal 34.

To provide for the retardation of the transfer of heat into and out of the heat absorbing case 68 and the chamber 6| the case is enclosed within a heat-transfer-retarding jacket comprising a group of discs 88, a wound-up strip 8| and a second group of discs 82. Before assembling the thermal switch within the casing, the discs are placed upon the inner face of the metal disc 12. The strip 8| is wound about the case 60, and that assembly is placed with the housing H. The discs 82 are placed adjacent the spiral strip 8| and the case 68. The discs 82 may be provided with spaced aligned notches at their peripheries to receive the wires 4| and 45, as shown in Fig. 2, or the discs 82 may be made smaller than the inside dimension of the tube H to allow the Wires 4! and 45 to straddle the outer peripheries of the discs. After the insulating members, case 60 and the cover 15 are assembled with the case 'H, these parts are secured together by spinning over the free end of the case H against the outer face of the cover at 85.

Instead Of using a cellular structure constructed of corrugated cardboard to provide the jacket of low heat conductivity between the heat absorbing, switch-containing case and the surrounding atmosphere, a double-wall glass vacuum bottle can be used. Since a vacuum bottle is a much better insulator than card-board, it can be made much smaller than the corrugated cardboard jacket; hence the entire switch unit can be made smaller than shown in Fig. 2. A unit using a vacuum bottle is disclosed in Figs. 5 through 8. Vacuum bottle 89 is housed within a sheet metal case 8| and is protected b a single layer of corrugated paper 82. Bottle 80 receives a thick cork stopper 83 cemented to discs 84 and 85 of sheet insulating material. Disc 84 supports a two stage thermal switch I80 (to be described) surrounded by a heat absorbin tube 86 from which the vacuum bottle is protected by corrugated paper at S? and 88. Disc 85 carries three terminals Bil, 9!, and 92 between which resistances 93 and 94 are connected. Terminals 99 and 92 are connected respectively with wires 35 and 38 of the diagram Fig. l. Terminals 9!], 9! and 52 are connected respectively with wires 85, 96 and 91 extending through the cork 83. The parts are permanently secured in assembled relation by spinning the case at 8Ia against the disc 85.

Thermal switch I00 comprises a metal bracket IOI attached to disc 84 and connected with wire 95. Bracket IOI carries contacts I02 and I03 on adjusting screws as shown in Fig. 8 and engageable, respectively, with contacts I04 and I05 on the free ends of blades I06 and I01, respectively, insulatingly supported by bracket IOI and connected, respectively, with wires 96 and 91. Blade I06 may close contacts I02, I04 at some intermediate temperature, such as 100 F., to short out resistance 93 in order to effect a part of the reduction of the voltage at which the regulator begins to regulate. Blade I0'I may close contacts I03I05 at some higher temperature such as 125 F. to short out resistance 94, while resistance 93 remains shorted, in order to complete the total reduction of charging voltage.

While the embodiments of the present invention as herein disclosed, constitute preferred forms it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A temperature-responsive unit for use with a storage battery and comprising a thermal switch, a heat absorbing body enclosing the switch, said body having an effect upon the thermal switch simulating the thermal effect of the elements of a storage battery upon a thermal switch located within the battery, and a heattransfer-retarding jacket enclosing the body and having an effect upon the thermal switch simulating the thermal effect of the walls of a storage battery case upon a thermal switch located within the battery, a resistance unit supported outside the jacket and connections for connecting the resistance unit in the circuit of the thermal switch.

2. A unit according to claim 1, in which the material of the heat absorbing body is a metal having relatively high specific heat and density and in which the thermal switch is mounted upon a closure for an opening in the housing.

3. A unit according to claim 1, in which the heat-transfer-retarding jacket is a cellular structure made of corrugated paper.

4. A unit according to claim 1, in which the heat absorbing container is a hollow, cylindrical, metallic body, and in which the heat-transferretarding jacket comprises a wrapping of layers of corrugated paper wound around the cylindrical surface of the body and a plurality of corrugated paper discs facing each end of the metallic body and the enclosing wrapping of corrugated paper.

5. A unit according to claim 1 in which the heat-transfer-retarding jacket is provided by a. double wall glass vacuum bottle, and in which there is a stopper for the bottle which supports the thermal switch.

WILLIAM J. RADY. 

